Gas extraction method for highway tunnel coal seam with gas outburst by component regional gridding

Abstract

The present application relates to the technical field of gas tunnel construction, in particular to a highway tunnel gas outburst coal seam component regional gridding gas extraction method, by dividing the region to be constructed into at least two gas to be discharged areas, then arranging the gas extraction pipeline structure along the extension direction of the gas tunnel, and then conducting extraction construction on all the gas to be extracted areas through the gas extraction pipeline structure, the present application forms the gas to be extracted area by dividing the gas to be discharged area, and then uses the gas extraction pipeline structure to extract the gas from all the gas to be extracted areas, so that the present application has the function of partitioned extraction of gas in specific implementation, and thus solves the technical defects in the related art that in long-term extraction, the overall extraction standard can only be judged by the gas extraction data at the hole, and it is impossible to determine whether there is excessive extraction or extraction is not in place.

Description

Technical Field

[0001] This invention relates to the field of gas tunnel construction technology, and in particular to a regional gridded gas drainage method for coal seam components in highway tunnels prone to gas outbursts. Background Technology

[0002] In gas outburst control, gas drainage is carried out according to the established scope. While highway tunnel gas tunnel specifications do not specify gas drainage, the "Coal Mine Gas Drainage Specification" and other coal mine specifications are followed. Drainage is categorized according to the coal seam exposure and tunnel excavation categories for un-depressurized shafts. The drainage volume is calculated based on the total gas volume and acceptable limits within the control area to determine the drainage rate. The initial drainage time is determined according to the "Detailed Rules for Prevention and Control of Coal and Gas Outbursts (2019 Edition)," which stipulates that the minimum drainage time for a gas tunnel must not be less than 60 days. During the drainage process, relevant parameters are strictly recorded to assess whether the standards are met. Only after compliance is achieved is the outburst prevention and control effect implemented inside the tunnel. During long-term drainage, judgment can only be made based on gas drainage data at the tunnel entrance. However, for the control of coal seams composed of multiple coal seams, the gas content and thickness of each seam are inconsistent, making it impossible to judge the drainage effect of each individual seam.

[0003] Currently, for gas control, the amount of gas to be pumped out is calculated based on the total amount of gas in the control area and the limit value to meet the standard. The initial pumping time (at least 3 months) is determined. Relevant parameters are recorded in the pump room at the tunnel entrance to estimate and judge whether the standard is met. After the standard is met, the coal seam is then tested for the effect of gas outburst prevention and control inside the tunnel. If the standard is not met, further pumping is required.

[0004] During long-term drainage, the overall drainage standard can only be judged by the gas drainage data at the tunnel entrance. However, when dealing with multiple coal seams, the thickness and gas content of each coal seam may be different, resulting in over-drainage or serious under-drainage of coal seams. Summary of the Invention

[0005] The main objective of this invention is to provide a regional gridded gas drainage method for coal seam components in highway tunnels prone to gas outbursts. This method aims to solve the technical problem that related technologies can only judge the overall drainage compliance by relying on gas drainage data at the tunnel entrance during long-term drainage. However, when dealing with multiple coal seams, the thickness and gas content of each coal seam may be different, leading to over-drainage or inadequate drainage of severely affected coal seams.

[0006] To achieve the above objectives, in a first aspect, the present invention proposes a regional gridded gas drainage method for coal seam components in a highway tunnel where gas outbursts occur, wherein the gas tunnel has a construction area.

[0007] The regional grid-based gas drainage method for coal seam components in highway tunnels prone to gas outbursts includes the following steps:

[0008] The area to be constructed is divided into at least two gas drainage zones; wherein each gas drainage zone is provided with at least one gas drainage hole, and all gas drainage holes penetrate the multi-coal seam group.

[0009] A gas extraction pipeline structure is arranged along the extension direction of the gas tunnel; wherein, the gas extraction pipeline structure includes an exhaust end located outside the gas tunnel and multiple air inlets located inside the gas tunnel, the number of the multiple air inlets being the same as the number of gas extraction holes and corresponding to each other in a one-to-one manner.

[0010] The gas extraction pipeline structure is used to carry out gas extraction construction in all the gas extraction areas.

[0011] Optionally, at least two of the gas extraction zones are arranged in a first preset order;

[0012] The steps of performing gas extraction construction on all the gas-to-be-extracted areas through the gas extraction pipeline structure include:

[0013] The gas extraction pipeline structure is used to sequentially extract gas from all the gas-to-be-extracted areas in the first preset order.

[0014] Optionally, each of the gas extraction zones is arranged with multiple hole groups in a second preset order, and each hole group includes at least two spaced gas extraction holes.

[0015] The step of sequentially draining all the gas-to-drain areas through the gas drainage pipeline structure in the first preset order includes:

[0016] When performing gas extraction construction on each gas extraction area through the gas extraction pipeline structure, all the hole groups on the gas extraction area are extracted sequentially according to the second preset order.

[0017] Optionally, each of the hole groups has a plurality of gas extraction holes arranged in a third preset order;

[0018] The step of performing gas extraction work on each gas extraction area through the gas extraction pipeline structure, and sequentially extracting all the hole groups on the gas extraction area according to the second preset order, includes:

[0019] When performing gas extraction construction on each gas extraction area through the gas extraction pipeline structure, the first gas extraction hole in the hole group of all the holes in the gas extraction area is extracted in the second preset order.

[0020] Detect and determine whether the current gas content in the first gas extraction hole reaches a preset target.

[0021] When the first current gas content reaches the preset index, all the remaining gas drainage holes in the hole group are sequentially used as the first gas drainage hole according to the third preset order, and corresponding drainage construction is carried out. When constructing each gas drainage hole, the step of detecting and judging whether the first current gas content in the first gas drainage hole reaches the preset index is repeated until the first current gas content corresponding to each of the remaining gas drainage holes reaches the preset index.

[0022] Optionally, after the step of detecting and determining whether the current gas content in the first gas extraction hole reaches a preset index, the method further includes:

[0023] If the first current gas content does not reach the preset index, the gas extraction construction of the first gas extraction hole in the hole group continues, and the process returns to the step of detecting and judging whether the first current gas content in the first gas extraction hole reaches the preset index, until the first current gas content reaches the preset index.

[0024] Optionally, before the step of sequentially performing gas extraction operations on all the gas-to-extraction areas through the gas extraction pipeline structure in the first preset order, the method further includes:

[0025] Detect and determine whether the second current gas content in the first gas extraction zone reaches the preset index;

[0026] The step of sequentially performing gas extraction operations on all gas-to-extraction areas through the gas extraction pipeline structure in the first preset order includes:

[0027] When the second current gas content reaches the preset index, the remaining gas extraction areas are sequentially designated as the first gas extraction area through the gas extraction pipeline structure according to the first preset order, and corresponding extraction construction is carried out. When constructing each gas extraction area, the step of detecting and judging whether the second current gas content in the first gas extraction area reaches the preset index is repeated until the second current gas content corresponding to each of the remaining gas extraction areas reaches the preset index.

[0028] Optionally, after detecting and determining whether the second current gas content in the first gas extraction zone reaches the preset index, the method further includes:

[0029] When the second current gas content does not reach the preset index, the gas extraction pipeline structure is used to extract gas from all the hole groups in the gas extraction area in the second preset order until the second current gas content in the first gas extraction area reaches the preset index.

[0030] Optionally, each of the aforementioned air inlets is equipped with a flow meter.

[0031] Optionally, the step of dividing the area to be constructed into at least two adjacent gas drainage zones includes:

[0032] Shotcrete is applied to the area to be constructed to form a corresponding surface to be discharged.

[0033] Multiple gas extraction holes are drilled at intervals on the surface to be discharged.

[0034] Based on the location information of the multiple gas extraction holes, the surface to be discharged is divided into zones to form at least two gas extraction zones.

[0035] Optionally, the step of dividing the area to be constructed into at least two gas drainage zones includes:

[0036] Based on the target parameter information of the multi-coal seam group, the gas reserves in the multi-coal seam group are determined;

[0037] The corresponding drainage time is determined based on the gas reserves.

[0038] The technical solution of this invention divides the area to be constructed into at least two gas emission zones, then arranges a gas extraction pipeline structure along the extension direction of the gas tunnel, and then performs gas extraction construction on all gas emission zones through the gas extraction pipeline structure. This invention divides the gas emission zone into gas emission zones, and then uses the gas extraction pipeline structure to perform gas extraction on all gas emission zones. This enables the invention to perform zoned gas extraction in specific implementation, thereby solving the technical defect in related technologies that, during long-term extraction, can only judge the overall extraction compliance based on the gas extraction data at the tunnel entrance, and cannot determine whether there is over-extraction or inadequate extraction. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0040] Figure 1 A flowchart illustrating the gridded gas drainage method for coal seam components in a highway tunnel gas outburst, as exemplified by this invention;

[0041] Figure 2 for Figure 1 A detailed flowchart of step S300 in the example;

[0042] Figure 3 for Figure 2 A detailed flowchart of step S310 in the example;

[0043] Figure 4 for Figure 1 Flowcharts of some embodiments of step S311 in the example;

[0044] Figure 5 for Figure 1 The flowchart of some specific embodiments of step A300 in the example is shown;

[0045] Figure 6 for Figure 1 A detailed flowchart of step S200 in the example;

[0046] Figure 7 Flowcharts of some specific embodiments of the present invention;

[0047] Figure 8 This is a schematic diagram illustrating the arrangement of gas extraction holes as an example of the present invention;

[0048] Figure 9 This is a schematic diagram of the gas control outline as an example of the present invention;

[0049] Figure 10 This is a schematic diagram illustrating the arrangement of gas extraction holes in the area to be constructed, as exemplified by this invention.

[0050] Figure 11 This is a side view of a gas extraction hole as an example of the present invention;

[0051] Figure 12 This is a schematic diagram illustrating the division of the emission zone as an example of the present invention;

[0052] Figure 13 This is a schematic diagram of an example of a hole group according to the present invention;

[0053] Figure 14 This is a schematic diagram illustrating the arrangement of gas extraction holes as an example of the present invention.

[0054] Explanation of reference numerals in the attached figures:

[0055] 100 Area awaiting construction 200 Tunnel outline 110 Gas waiting area 300 Gas control outline 111 Hole Group 400 Climbing the steps 10 Gas extraction hole 500 Go down the steps

[0056] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0058] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the mechanisms in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0059] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0060] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0061] The inventive concept of the present invention will be further explained below with reference to some specific embodiments.

[0062] This invention proposes a regional gridded gas drainage method for coal seam components in highway tunnels prone to gas outbursts.

[0063] like Figures 1 to 14 As shown, an embodiment of the present invention is proposed for the regional gridded gas drainage method for coal seam components in highway tunnels prone to gas outbursts.

[0064] For example, in this embodiment, 200 is the tunnel outline of the gas tunnel, and 300 is the gas control outline of the gas tunnel.

[0065] In this embodiment, please refer to Figure 1 This type of highway tunnel gas outburst coal seam component regional grid gas drainage method, with 100 areas to be constructed inside the gas tunnel;

[0066] The regional grid-based gas drainage method for coal seam components in highway tunnels prone to gas outbursts includes the following steps:

[0067] S100, Divide the area to be constructed 100 into at least two gas drainage zones 110; wherein, each gas drainage zone 110 is provided with at least one gas drainage hole 10, and all gas drainage holes 10 penetrate multiple coal seams.

[0068] In this embodiment, when dividing the gas drainage area 110, the following process may be used, but is not limited to: First, multiple gas drainage holes 10 that are spaced apart and penetrate multiple coal seam groups are drilled in the area to be constructed 100. Then, the gas drainage area 110 is divided according to the shape of the working face, the shape of the construction face, and the construction technology used during construction.

[0069] It is particularly important to clarify that, in the exemplary technology, taking a gas tunnel constructed using the short-step method as an example, when dividing the gas drainage area 110, the constructed steps are divided into the first drainage area, and the tunnel face is divided into the second drainage area. Then, the first and second drainage areas are each further divided into at least two corresponding gas drainage areas 110. That is, the first drainage area includes at least one gas drainage area 110, and the second drainage area also includes at least two gas drainage areas 110. Each gas drainage area 110 includes at least one gas drainage hole 10. This division method enables the present invention to perform gas drainage on each gas drainage area 110 during specific implementation. For example, when drilling the gas drainage hole 10, the gas drainage hole 10 can be horizontal or gradually widened from the tunnel face towards the extension direction of the gas tunnel at a certain angle to the central axis of the gas tunnel.

[0070] S200. A gas extraction pipeline structure is arranged along the extension direction of the gas tunnel; wherein, the gas extraction pipeline structure includes an exhaust end set outside the gas tunnel and multiple air inlets set inside the gas tunnel, and the number of multiple air inlets is the same as that of the gas extraction holes 10 and they are connected one by one.

[0071] In this embodiment, when arranging the gas extraction pipeline structure, the pipeline structure of this invention example arranges a main steel pipe pipeline with a diameter of 300mm and a wall thickness of 6.5mm along the longitudinal direction of the tunnel, which runs through the completed construction area of ​​the tunnel and extends to the working face and outside the tunnel at both ends respectively. Two transverse first branch pipes and one lower first branch pipe are set at the upper step 400 of the tunnel. The first branch pipe is a steel pipe with a diameter of 200mm and a wall thickness of 3.5mm. The area extraction pipes at the upper and lower steps 500 are steel pipes with a diameter of 150mm and a wall thickness of 3.5mm. A second branch pipe with a diameter of 25mm, which is a galvanized steel pipe, is welded on the area extraction pipe. The third branch pipe buried in the tunnel body is connected with a 35mm transparent soft rubber and is a PPR pipe with an outer diameter of 25mm.

[0072] Connection methods between various pipelines: Custom-made tee connections are used between steel pipes of different diameters (300mm and 200mm, 200mm and 150mm). Smaller diameter steel pipes are connected at a 45° angle to larger diameter steel pipes. Steel pipes are connected using flanges with gaskets between them, secured with bolts to prevent air leakage. Rubber hoses and steel pipes, as well as rubber hoses and PPR pipes, are connected using heat fusion, with external reinforcement of 2 to 8 gauge steel wire to improve the sealing of the connection.

[0073] During the gas outburst control of a tunnel on a certain highway, the procedures and specifications were strictly followed. The gas outburst control involved designing numerous drainage holes to extract gas from specific areas within the tunnel, reducing gas pressure and content to meet requirements before tunnel construction. During the construction of drainage hole 10, drainage holes were arranged at the 400mm face of the upper bench and the 500mm platform of the lower bench. The drainage holes were drilled using a hydraulic drilling rig, with a 25mm diameter PPR first branch pipe installed along its entire length.

[0074] The extraction pipeline structure of this invention comprises a first branch pipe of PPR with a diameter of 25mm, a second branch pipe of soft rubber with a diameter of 25mm, a galvanized steel pipe with a diameter of 25mm, a seamless steel pipe with a diameter of 150mm, a seamless steel pipe with a diameter of 200mm, and a seamless steel pipe with a diameter of 300mm, as well as connectors and flanges, gaskets, and bolts of corresponding diameters.

[0075] Normal flow matching: 361 drainage pipes: 36 pipes with a diameter of 25mm are matched with one 150mm steel pipe of equal area; 4 pipes with a diameter of 150mm are matched with one 300mm steel pipe of equal area; 2 pipes with a diameter of 300mm are equivalent to one 426mm steel pipe. Considering actual usage, under high negative pressure drainage, the 300mm steel pipe drives the 200mm steel pipe, which in turn drives the 150mm and 25mm steel pipes; the flow velocity in subsequent pipes decreases; at the same time, gas exists in the gaps between the rock strata and coal seam and overflows into the 25mm pipe. In the closed space of the tunnel rock mass, drainage is considered to fill the pipe diameter by 50%. At the same time, laying a 426mm diameter pipeline along the entire 1500m longitudinal length of the tunnel is too expensive and cannot be used, resulting in a huge cost burden. The actual configuration adopts the drainage pipeline structure of the right line of a certain tunnel: one 300mm steel pipe is arranged longitudinally along the tunnel and extends to the tunnel entrance, three 200mm pipes extend to the working face and the lower bench 500, and then 10 150mm pipes are connected to 36 25mm drainage pipes to form the drainage pipeline.

[0076] Gas Flow: After the negative pressure drainage is initiated, the gas concentration in the first branch pipe is 0, and the pressure is negative. The C7 and C8 coal seams have higher gas pressure and content, resulting in significant pressure and concentration drops. Gas overflows from areas of high concentration and pressure into the first branch pipe through voids and channels within the coal seam. The high-concentration gas from the coal seam and rock mass converges into a 100mm diameter steel pipe via the first and second branch pipes. The gas in the steel pipe then converges into the second branch pipe, and the gas in the second branch pipe flows back to the first branch pipe. Finally, the gas is discharged outside the tunnel through the main pipe. After a certain period of drainage, the gas concentration in the coal seam and rock mass is reduced to the specified value (gas concentration below 8m³). 3 / ton of coal, gas pressure less than 0.74MPa).

[0077] The drainage pipeline structure of the coal seam group with zero net distance formed by C7 and C8 in the right tunnel of a certain tunnel shall be such that after the first branch pipe is installed, it is exposed at least 50cm outside the working face and the lower platform; one end of the second branch pipe with a diameter of 25mm soft rubber is connected to the exposed first branch pipe with a diameter of 25mm PPR, and the other end is connected to the galvanized steel pipe with a diameter of 25mm.

[0078] In this invention example, the protruding pipe sections of the third branch pipe and the second branch pipe are connected by heat fusion, and No. 8 steel wire is tied firmly to both ends of the second branch pipe.

[0079] The other end of the protruding pipe section of the second branch is welded to a steel pipe with a diameter of 150mm;

[0080] The connection between the second branch pipe and the first branch pipe, and between the first branch pipe and the main pipe, is achieved through a special-shaped tee, a 150mm diameter steel pipe flange connection point, and a single-line valve is installed.

[0081] Flange connections are used between pipes of the same diameter. For example, flange connections are used for connections between tee pipes and straight pipes.

[0082] The pipeline structure is determined according to the coverage of the drainage pipes in different areas. Each 150mm steel pipe is connected to a 25mm drainage pipe, which is responsible for the gas drainage within the corresponding area.

[0083] When the gas concentration and pressure in any 150mm pipeline area reach the specified standard, closing the single-line valve will stop the pumping, which will cause the negative pressure in other pipeline areas to increase, the flow rate to be faster, and improve the pumping effect.

[0084] This invention specifies the exact quantities for matching various pipe diameters, clearly defining that a 150mm pipe can connect up to 36 25mm diameter pipes, 4 150mm pipes can be matched with 1 200mm pipe, and 3 200mm pipes can be matched with 1 300mm steel pipe.

[0085] The second branch pipe is connected to the protruding pipe sections of the first and second branch pipes by heat fusion and binding. This can completely seal the pipe and prevent air leakage, which is more effective than simply binding it with wire.

[0086] The first branch pipe is connected to the second branch pipe, and the first branch pipe is connected to the main pipe using a tee. The tee is custom-made by the manufacturer and uses a flange connection, which provides better sealing than traditional welding.

[0087] The 45° angle between the tees improves airflow and reduces air volume loss.

[0088] S300, gas extraction construction is carried out in all gas extraction areas 110 through the gas extraction pipeline structure.

[0089] In this embodiment, when performing extraction, a method of extraction by dividing the area into sections and holes can be used, but is not limited to this method. This method can ensure the extraction effect of each area.

[0090] In this embodiment, the area to be constructed 100 is divided into at least two gas emission zones, and then a gas extraction pipeline structure is arranged along the extension direction of the gas tunnel. Next, the gas extraction pipeline structure is used to extract gas from all gas emission zones 110. This invention divides the gas emission zone into gas emission zones 110, and then uses the gas extraction pipeline structure to extract gas from all gas emission zones 110. This enables the invention to perform zoned gas extraction in specific implementations, thereby solving the technical defect in related technologies where, during long-term extraction, the overall extraction compliance can only be judged by the gas extraction data at the tunnel entrance, and it is impossible to determine whether there is over-extraction or inadequate extraction.

[0091] In some specific embodiments, at least two gas extraction zones 110 are arranged in a first preset order;

[0092] The steps for gas extraction construction in all gas extraction zones 110 through the gas extraction pipeline structure include:

[0093] S310. Gas extraction and drainage operations are carried out in all gas extraction zones 110 in sequence according to the first preset order through the gas extraction pipeline structure.

[0094] In this embodiment, by using a sequential extraction method, the present invention can extract gas through each gas extraction hole 10 in each area to be extracted, thereby solving the defect in related technologies that cannot extract gas from every position in the area to be extracted.

[0095] It should be specifically and clearly stated that, in the exemplary technology, a drainage area is arranged with holes numbered 1#, 2# and 3# in a top-to-bottom order. When carrying out drainage construction, the order can be 2# to 3# to 1#, 1# to 2# to 3#, or 3# to 2# to 1#.

[0096] In some specific embodiments, each gas extraction zone 110 is arranged with multiple hole groups 111 in a second preset order, and each hole group 111 includes at least two spaced gas extraction holes 10.

[0097] The steps for sequentially draining gas from all gas-to-drain areas 110 using the gas drainage pipeline structure in the first preset sequence include:

[0098] S311. When performing gas drainage construction on each gas drainage area 110 through the gas drainage pipeline structure, all hole groups 111 on the gas drainage area 110 shall be drained in sequence according to the second preset order.

[0099] It should be specifically and clearly stated that, in the exemplary technology, a gas extraction hole 10, gas extraction hole 10, and gas extraction hole 10 numbered sequentially from top to bottom are arranged in a gas extraction area. When performing extraction construction, the sequence can be gas extraction hole 10 to gas extraction hole 10 to gas extraction hole 10 to gas extraction hole 10, or gas extraction hole 10 to gas extraction hole 10 to gas extraction hole 10 to gas extraction hole 10, or gas extraction hole 10 to gas extraction hole 10 to gas extraction hole 10 to gas extraction hole 10.

[0100] In some specific embodiments, each hole group 111 has multiple gas extraction holes 10 arranged in a third preset order;

[0101] When performing gas drainage work on each gas drainage area 110 through the gas drainage pipeline structure, the steps of sequentially performing gas drainage work on all hole groups 111 on the gas drainage area 110 according to the second preset order include:

[0102] S311a. When performing gas extraction construction on each gas extraction zone 110 through the gas extraction pipeline structure, the first gas extraction hole 10 in the hole group 111 of the gas extraction zone 110 is extracted according to the second preset order.

[0103] S311b: Detect and determine whether the current gas content in the first gas extraction hole 10 has reached the preset index;

[0104] S311c When the first current gas content reaches the preset index, all remaining gas drainage holes 10 in the hole group 111 are sequentially used as the first gas drainage hole 10 according to the third preset order, and corresponding drainage construction is carried out. When constructing each gas drainage hole 10, the step of detecting and judging whether the first current gas content in the first gas drainage hole 10 reaches the preset index is repeated until the first current gas content corresponding to each remaining gas drainage hole 10 reaches the preset index.

[0105] In some specific embodiments, after the step of detecting and determining whether the current gas content in the first gas extraction hole 10 reaches a preset index, the method further includes:

[0106] S311d. When the first current gas content does not reach the preset index, the gas extraction construction of the first gas extraction hole 10 in the hole group 111 continues, and the process returns to the step of detecting and judging whether the first current gas content in the first gas extraction hole 10 has reached the preset index, until the first current gas content reaches the preset index.

[0107] In some specific embodiments, before the step of sequentially performing gas extraction operations on all gas extraction zones 110 according to a first preset sequence via the gas extraction pipeline structure, the method further includes:

[0108] A310. Detect and determine whether the second current gas content in the first gas extraction zone 110 reaches the preset index;

[0109] A320. The steps of performing gas extraction construction on all gas extraction zones 110 in sequence according to the first preset order through the gas extraction pipeline structure include:

[0110] A330. When the second current gas content reaches the preset index, the remaining gas extraction zones 110 are sequentially designated as the first gas extraction zone 110 through the gas extraction pipeline structure in the first preset order, and corresponding extraction construction is carried out. When constructing each gas extraction zone 110, the step of detecting and judging whether the second current gas content in the first gas extraction zone 110 reaches the preset index is repeated until the second current gas content corresponding to each of the remaining gas extraction zones 110 reaches the preset index.

[0111] In some specific embodiments, a flow meter is installed at each air inlet.

[0112] In this embodiment, by installing a flow meter at each air inlet, the present invention can record the gas content of each gas extraction hole 10 during implementation, thereby enabling the present invention to accurately determine the gas content of each gas extraction hole 10 during implementation.

[0113] In some specific embodiments, the step of dividing the area to be constructed 100 into at least two adjacent gas drainage zones 110 includes:

[0114] S210. Apply shotcrete to the construction area 100 to form the corresponding surface to be discharged.

[0115] S220. Drill multiple spaced gas extraction holes 10 on the surface to be discharged.

[0116] S230. Based on the location information of multiple gas extraction holes 10, the surface to be discharged is divided into zones to form at least two gas extraction zones.

[0117] In some specific embodiments, the step of dividing the area to be constructed 100 into at least two gas drainage zones 110 includes:

[0118] S400. Determine the gas reserves in the multi-coal-seam group based on the target parameter information.

[0119] S500. Determine the corresponding drainage time based on the gas reserves.

[0120] Currently, for gas control, the amount of gas to be pumped out is calculated based on the total amount of gas in the control area and the limit value to meet the standard. The initial pumping time (at least 3 months) is determined. Relevant parameters are recorded in the pump room at the tunnel entrance to estimate and judge whether the standard is met. After the standard is met, the coal seam is then treated for outburst prevention inside the tunnel. If the standard is not met, further pumping is required.

[0121] During long-term drainage, the overall drainage standard can only be judged by the gas drainage data at the tunnel entrance. However, when dealing with multiple coal seams, the thickness and gas content of each coal seam may be different, resulting in over-drainage or serious under-drainage of coal seams.

[0122] However, for the treatment of coal seam groups composed of multiple coal seams, the gas content and thickness of each coal seam are inconsistent, making it impossible to judge the drainage effect of each coal seam.

[0123] When multiple coal seams are being drained, even when the overall target is met, the target may not be met for the more difficult-to-drain coal seams. This requires further drainage of all coal seams, which extends the construction period and increases costs.

[0124] This method uses a grid to distinguish the borehole locations according to the different coal seam drainage ranges, and divides the drainage areas into different zones according to the different 500-degree gaps between the upper and lower steps.

[0125] Different coal seams and regions are divided into separate grids. When arranging the drainage pipelines, drainage holes and functions in the same coal seam area are divided into the same grid and connected to the same pipeline. This results in a unique drainage pipeline structure.

[0126] During the drainage process, based on the data collected at the pumping station at the tunnel entrance and the data collected in different grid areas, we comprehensively consider closing the grid pipelines of the easily extractable coal seams that have already met the initial standards, and accelerating the drainage efficiency of other grids.

[0127] For gas drainage in multiple coal seams, precise location can be achieved, accelerating gas drainage, improving drainage efficiency, and shortening drainage time.

[0128] Based on the characteristics of the C7 and C8 coal seams in the right line of the Tianchengba Tunnel, and considering the designed number of boreholes, the area was divided into a 400mm drainage zone on the upper bench and a 500mm drainage zone on the lower bench. Drainage holes within the same coal seam were grouped into one category, and then further subdivided into different grids based on the different zones: 4 grids for the C7 coal seam and 7 grids for the C8 coal seam, for a total of 11 grids. Drainage pipelines were designed according to these grids. (See attached diagram). Figure 3 The exhaust piping structure consists of a 25mm diameter PPR pipe 1, a 25mm diameter soft rubber hose 2, a 25mm diameter galvanized steel pipe 3, a 150mm diameter seamless steel pipe 4, a 200mm diameter seamless steel pipe 5, and a 300mm diameter seamless steel pipe 6. A special-shaped tee 1 is installed between the 150mm and 200mm pipes, and a special-shaped tee 2 is installed between the 200mm and 300mm pipes. A simple ventilation valve is specially designed near the tee 1. A 2-point faucet with a switch is welded onto the 150mm pipe. The simple ventilation valve is open during normal exhaust, and the faucet is closed. These two devices can be turned on and off as needed.

[0129] When draining gas from a coal seam prone to gas outbursts, the gas reserves A1 are calculated based on the coal seam parameters before drainage. Once the drainage reaches the standard, the specific drainage volume Q1 is determined. The gas content at the end of drainage is 8 m3 / ton of coal. During drainage, the remaining gas content Q and the volume Q2 already drained are calculated based on the data recorded daily by the pumping station outside the tunnel and the computer records. At the same time, the gas content is measured and recorded three times a day, and a curve is generated to compare the gas content collected by the drainage pipes outside the tunnel. When the total extraction reaches approximately 80%, check the gas content of pipe 4 in each grid. If the gas content of the corresponding coal seam is deduced to be below 8%, temporarily close the ventilation valve of the corresponding grid. At this time, the negative pressure extraction pump continues to maintain its current power to extract gas from the coal seam that has not met the standard, in order to accelerate the gas extraction effect of the coal seams in other grids. Extract all the gas from the C8 coal seam. When the C8 coal seam content is detected to be within the standard, open the previously closed valve of the C7 coal seam grid and continue to extract all coal seams until the total extraction volume is reached. Then, use the gas content at the tunnel entrance and the gas content of the 12 grids to verify that the extraction meets the standard. Details are as follows:

[0130] When draining gas from a coal seam prone to gas outbursts, the gas reserves A1 are calculated based on the coal seam parameters before drainage. Once the drainage reaches the standard, the specific drainage volume Q1 is determined. The gas content at the end of drainage is 8 m3 / ton of coal. During drainage, the remaining gas content A12 and the volume of gas already drained Q2 are calculated based on the data recorded daily by the pumping station outside the tunnel and the computer records. At the same time, the gas content is measured and recorded three times a day by turning on the water tap, and a curve is generated to compare with the gas content summarized by the drainage pipe outside the tunnel. When the total extraction reaches about 80%, check the gas content of pipe 4 in each grid. When the gas content is below 8%, temporarily close the ventilation valve of the corresponding grid. At this time, the negative pressure extraction pump continues to maintain the current power to accelerate the gas extraction effect of coal seams in other grids until all 5 grid valves of C7 coal seam are closed and all C8 coal seam gas is extracted. When the C8 coal seam content is found to be up to standard, open the previously closed C7 coal seam grid valve and continue to extract all coal seams until the total extraction volume is reached. Then, use the tunnel entrance to measure the gas content and the gas content of 12 grids to verify that the extraction meets the standard.

[0131] The following is a more detailed explanation:

[0132] Step S201: Collect data from C7 and C8 coal seams based on their characteristics, parameters, and the determined extraction area.

[0133] Step S202: Calculate the gas reserves W = W1 + W2 + W3 in the coal seam and corresponding rock strata.

[0134] W - Gas reserves, W1 - Gas reserves of all coal seams within the extraction range, W2 - Gas content of all coal seams in the affected area outside the extraction area, W3 - Gas content of rock strata within the extraction area.

[0135] Step S203, based on the "Coal Mine Gas Drainage Specification" and the actual site conditions, determines the drainage method as "difficult to drain".

[0136] Step S204: Calculate the required drainage volume Q1, the comprehensive drainage rate, and the initial drainage time (93 days) based on the critical indicator of gas content (8 m3 / ton of coal) and related parameters.

[0137] Step S205: After checking and accepting that the sealing quality of the extraction hole, the extraction pipeline, and the extraction equipment all meet the requirements, proceed to the next step.

[0138] Step S206: Start the negative pressure vacuum pump equipment to begin extraction. Start the gas extraction station parameter monitoring instrument within the gas extraction station to continuously monitor parameters such as methane concentration, flow rate, negative pressure, leaked gas concentration in the pump room, and pump shaft temperature in the gas extraction pipeline. Calculate the initial gas extraction volume QH, QC, and the total remaining gas content in the coal seam Q2. Proceed to the next step.

[0139] Step S207: Sequentially open the water taps in the 12 grids of the C7 and C8 coal seams inside the tunnel, detect and record the gas content of the drainage branch of each grid, and take the average value of three measurements per day.

[0140] Step S208: Record the data from the orifice plate flowmeters for each branch of the grid, taking the average of three readings per day. Calculate the cumulative flow rate and mixed flow rate QH7 and QH8 for the day of operation. Combined with the gas concentration xi from S206, calculate the pure gas flow rates QC7 and QC8 respectively, and deduce the remaining gas content Q7 and Q8 in coal seams C7 and C8. Continue recording and calculating the remaining gas content Q7 of the coal seam. If it is less than the critical value, proceed to step S209; otherwise, continue pumping.

[0141] Step S209: Close the five ventilation valves of the C7 coal seam grid branch and only pump out the C8 coal seam drainage hole until the residual gas content of the corresponding coal seam in the C8 coal seam grid branch is lower than the critical value, then proceed to step S211.

[0142] Step S210: Open all grid valves in C7 and continue pumping until the remaining gas content in the C7 coal seam is less than the critical value. Simultaneously, calculate the total gas drainage volume QH, QC, and Q2 based on the data from the gas drainage parameter instrument at the tunnel entrance. If QC < QC7 + QC8, proceed to step S209; otherwise, continue pumping until QC < QC7 + QC8 is satisfied.

[0143] Step S211: Continue pumping for 3 days, then end the pumping process.

[0144] By dividing the construction area 100 into at least two gas emission zones, and then arranging gas extraction pipeline structures along the extension direction of the gas tunnel, the gas extraction pipeline structures are then used to perform gas extraction construction on all gas emission zones 110. This invention divides the gas emission zone into gas emission zones 110, and then uses gas extraction pipeline structures to perform gas extraction on all gas emission zones 110. This enables the invention to perform zoned gas extraction in specific implementations, thereby solving the technical defects in related technologies where, during long-term extraction, the overall extraction compliance can only be judged by the gas extraction data at the tunnel entrance, and it is impossible to determine whether there is over-extraction or inadequate extraction.

[0145] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for regional gridded gas drainage of coal seam components in highway tunnels prone to gas outbursts, characterized in that, The gas tunnel contains an area awaiting construction. The regional grid-based gas drainage method for coal seam components in highway tunnels prone to gas outbursts includes the following steps: The area to be constructed is divided into at least two gas drainage zones; each gas drainage zone is provided with at least one gas drainage hole, and all gas drainage holes penetrate multiple coal seams. A gas extraction pipeline structure is arranged along the extension direction of the gas tunnel; wherein, the gas extraction pipeline structure includes an exhaust end located outside the gas tunnel and multiple air inlets located inside the gas tunnel, the number of the multiple air inlets being the same as the number of gas extraction holes and corresponding to each other in a one-to-one manner. The gas extraction pipeline structure is used to carry out gas extraction construction in all the gas extraction areas. At least two of the gas extraction zones are arranged in a first preset order; The steps of performing gas extraction construction on all the gas-to-be-extracted areas through the gas extraction pipeline structure include: The gas extraction pipeline structure is used to sequentially extract gas from all the gas-to-extraction areas in the first preset order. Each of the gas extraction zones is arranged with multiple groups of holes in a second preset order, and each group of holes includes at least two spaced gas extraction holes. The step of sequentially draining all the gas-to-drain areas through the gas drainage pipeline structure in the first preset order includes: When performing gas extraction construction on each gas extraction area through the gas extraction pipeline structure, all the hole groups on the gas extraction area are extracted in sequence according to the second preset order. Each of the aforementioned hole groups has multiple gas extraction holes arranged in a third preset order; The step of performing gas extraction work on each gas extraction area through the gas extraction pipeline structure, and sequentially extracting all the hole groups on the gas extraction area according to the second preset order, includes: When performing gas extraction construction on each gas extraction area through the gas extraction pipeline structure, the first gas extraction hole in the hole group of all the holes in the gas extraction area is extracted in the second preset order. Detect and determine whether the current gas content in the first gas extraction hole reaches a preset target. When the first current gas content reaches the preset index, all the remaining gas drainage holes in the hole group are sequentially used as the first gas drainage hole according to the third preset order, and corresponding drainage construction is carried out. When constructing each gas drainage hole, the step of detecting and judging whether the first current gas content in the first gas drainage hole reaches the preset index is repeated until the first current gas content corresponding to each of the remaining gas drainage holes reaches the preset index.

2. The regional gridded gas drainage method for coal seam components in highway tunnels as described in claim 1, characterized in that, After the step of detecting and determining whether the current gas content in the first gas extraction hole reaches the preset index, the method further includes: If the first current gas content does not reach the preset index, the gas extraction construction of the first gas extraction hole in the hole group continues, and the process returns to the step of detecting and judging whether the first current gas content in the first gas extraction hole reaches the preset index, until the first current gas content reaches the preset index.

3. The regional gridded gas drainage method for coal seam components in highway tunnels as described in claim 2, characterized in that, Before the step of sequentially performing gas extraction operations on all gas-to-extraction areas through the gas extraction pipeline structure in the first preset order, the method further includes: Detect and determine whether the second current gas content in the first gas extraction zone reaches the preset index; The step of sequentially performing gas extraction operations on all gas-to-extraction areas through the gas extraction pipeline structure in the first preset order includes: When the second current gas content reaches the preset index, the remaining gas extraction areas are sequentially designated as the first gas extraction area through the gas extraction pipeline structure according to the first preset order, and corresponding extraction construction is carried out. When constructing each gas extraction area, the step of detecting and judging whether the second current gas content in the first gas extraction area reaches the preset index is repeated until the second current gas content corresponding to each of the remaining gas extraction areas reaches the preset index.

4. The regional gridded gas drainage method for coal seam components in highway tunnels as described in claim 3, characterized in that, After detecting and determining whether the second current gas content in the first gas extraction zone reaches the preset index, the method further includes: When the second current gas content does not reach the preset index, the gas extraction pipeline structure is used to extract gas from all the hole groups in the gas extraction area in the second preset order until the second current gas content in the first gas extraction area reaches the preset index.

5. The regional gridded gas drainage method for coal seam components in highway tunnels as described in any one of claims 1 to 4, characterized in that, Each of the aforementioned air inlets is equipped with a flow meter.

6. The regional gridded gas drainage method for coal seam components in highway tunnels as described in any one of claims 1 to 4, characterized in that, The step of dividing the area to be constructed into at least two adjacent gas drainage zones includes: Shotcrete is applied to the area to be constructed to form a corresponding surface to be discharged. Multiple gas extraction holes are drilled at intervals on the surface to be discharged. Based on the location information of the multiple gas extraction holes, the surface to be discharged is divided into zones to form at least two gas extraction zones.

7. The regional gridded gas drainage method for coal seam components in highway tunnels as described in any one of claims 1 to 4, characterized in that, The step of dividing the area to be constructed into at least two gas drainage zones includes: Based on the target parameter information of the multi-coal seam group, the gas reserves in the multi-coal seam group are determined; The corresponding drainage time is determined based on the gas reserves.

Images